DEC Opcodes
Reference for DEC computers
About
Explore the instruction sets of legendary DEC computers like the PDP and VAX. This app provides detailed information on each instruction, historical context, and interactive lessons. Discover the machines that shaped modern computing.
What's New in DEC Opcodes
1.9
July 10, 2026
What's New in v1.9 • DEC Glossary - Searchable guide to 45+ terms across buses, memory, storage, I/O, processors, software, and DEC culture • PDP-11 instructions added - MFPI, MFPD, MTPI, MTPD (previous-space memory access) and SPL (set priority level) • Memory Maps corrected - Separate PDP-11/45 (256KB) and PDP-11/70 (4MB) layouts; KW11-L and KW11-P clocks added to I/O page; byte units for PDP-11 and VAX • Official DEC handbooks linked - Architecture Handbook PDFs from bitsavers for all five systems in Programming Resources • System landing page setting - Choose whether tapping a system opens the instruction list or the system info page • PiDP-8 Quick Start expanded - OS/8 first commands, paper tape bootstrap sequence, Spacewar! controls, TSS/8 multi-user login, USB storage guide • PDP-1 toggle programs fixed - Correct memory addresses and proper ADD-based counting loop • Dynamic Type support - All sidebar and card text now scales with your preferred font size • Accessibility improved - Better VoiceOver labels and touch targets throughout • Faster launch - Removed artificial splash screen delay
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FAQ
What DEC architectures does DEC Opcodes cover?
DEC Opcodes covers five iconic DEC architectures: PDP-1 (1960), PDP-8 (1965), PDP-10 (1966), PDP-11 (1970), and VAX (1977). It provides detailed instruction sets, system specifications, and historical context for each.
What kind of information is provided for each instruction in DEC Opcodes?
For every instruction, DEC Opcodes offers a full description, octal and hex encoding, flags affected, addressing modes, word count, cycle counts, and assembly code examples. It also includes implementation notes and historical context.
Does DEC Opcodes have interactive lessons?
Yes, DEC Opcodes includes interactive lessons on assembly language and console operations, which are ideal for users with an emulator. These lessons help users understand the practical application of the instruction sets.
What are the design features of DEC Opcodes?
DEC Opcodes is beautifully designed with system-specific accent colors, five themes including Terminal green and Blinkenlights orange, and full Dark Mode support. It's built for exploration with instant search and filtering capabilities.
Is DEC Opcodes available on multiple devices?
Based on the provided data, DEC Opcodes is supported on iPhone and iPad. This makes it accessible for users on Apple's mobile and tablet platforms.
How often is DEC Opcodes updated?
The latest version of DEC Opcodes is 1.8, and it was last updated on May 26, 2026. This indicates a recent update, suggesting ongoing development and support for the application.
What is the user sentiment for DEC Opcodes?
DEC Opcodes has a perfect rating of 5.0 stars from 3 ratings. This high rating suggests very positive user sentiment and satisfaction with the app's content and functionality.
Does DEC Opcodes have ads?
No, DEC Opcodes does not contain advertisements. The application is free to download and use without any ad interruptions.